During shutdowns of the nuclear reactor it is necessary to carry out checking, maintenance and repair operations on the steam generators.
For this purpose use is made of servicing tools or checking probes, which are carried by a displacement device fixed in the steam generator water container located underneath the tube plate.
Certain checks or certain servicing operations require the tool or the checking probe to be placed in a perfectly centered position relative to the tube into which it is introduced. It may also be necessary to absorb loads, if the tool is subjected to a thrust tending to move it out of the tube.
Servicing tools or checking probes for steam generator tubes generally comprise a body of elongate shape adapted to be introduced into the tube to the desired height. In the majority of cases, it is necessary to achieve perfect alignment between the axis of the elongate body of the tool or checking probe and the axis of the tube in which the operation is carried out.
No pivoting means are known for achieving perfect centering of a servicing tool in a steam generator tube i.e., a means making it possible to align the axes of the servicing tool and of the tube in an extremely accurate manner.